Bike stops after 15 seconds iddling

Hi all. After 9 month with my Maxim xj700 1985 sitting at home trying to fix it I finally found an old mechanic 35 miles from my home. After 2 week he had her running great, pick her up ride home at 65mph for 35 miles. Next day I ride her to work and back, same speed but when I got to my garage started to "burping" and stops. Started her again, no problem, after 10 seconds same "burping" and stops. 3 days and so the same, start really good, idle for 10-15 seconds and stops as is running out of gas. Checked the fuel from de percock comin out strong, changed de fuel filter (have one in the outside line before carbs), the fuel line is clear so I can see fuel running good... Carbs were cleaned and diaphragms were replaced, floats up to level and everything was ok...for two days... Anyone had the same problem? Any idea where I shoukl look? Thanks

 

First thought is stuck float, but that should only take out one cylinder at a time. I'd crack the drains on each bowl and see if any are not getting gas. Do you have the original vacuum petcock? How are you testing it? On prime? Maybe it's not pulling enough vac for full flow on 'on'?

 

Take the plugs out and see how they look when it dies.

Maybe the starter circuit is being funky.

Doesn't sound like the issue I had with a tci that would just kill the bike and then after ten minutes be okay again, but I thought I'd throw in something else to worry about.